One type of internal combustion engines typically employs cylinders which compress a fuel and air mixture such that, upon firing of a spark plug associated with each cylinder, the compressed mixture ignites. The expanding combustion gases resulting therefrom move a piston within the cylinder. Upon reaching an end of its travel in one direction within the cylinder, the piston reverses direction to compress another volume of the fuel and air mixture. The resulting mechanical kinetic energy can be converted for use in a variety of applications, such as, propelling a vehicle or generating electricity, for example.
Another type of internal combustion engine, known as a compression ignition engine, uses a highly-compressed gas (e.g., air) to ignite a spray of fuel released into a cylinder during a compression stroke. In such an engine, the air is compressed to such a level as to achieve auto-ignition of the fuel upon contact between the air and fuel. The chemical properties of diesel fuel are particularly well suited to such auto-ignition.
The concept of auto-ignition is not limited to diesel engines, however, and has been employed in other types of internal combustion engines as well. For example, a self-igniting reciprocating internal combustion engine can be configured to compress fuel in a main combustion chamber via a reciprocating piston. In order to facilitate starting, each main combustion chamber is associated with a prechamber, particularly useful in starting cold temperature engines. Fuel is injected into not only the main combustion chamber, but also the combustion chamber of the prechamber, as well, such that, upon compression by the piston, a fuel and air mixture is compressed in both chambers. A glow plug or other type of heater is disposed within the prechamber to elevate the temperature therein sufficiently to ignite the compressed mixture. The combustion gases resulting from the ignition in the prechamber are then communicated to the main combustion chamber.
Other types of internal combustion engines use natural gas as the fuel source and include at least one piston reciprocating within a respective cylinder. A spark plug is positioned within a cylinder head associated with each cylinder and is fired on a timing circuit such that upon the piston reaching the end of its compression stroke, the spark plug is fired to thereby ignite the compressed mixture.
In still further types of internal combustion engines, prechambers are employed in conjunction with natural gas engines. Given the extremely high temperatures required for auto-ignition with natural gas and air mixtures, glow plugs or other heat sources such as those employed in typical diesel engines can be ineffective. Rather, a prechamber is associated with each cylinder of the natural gas engine and is provided with a spark plug to initiate combustion within the prechamber which can then be communicated to the main combustion chamber. Such a spark-ignited, natural gas engine prechamber is provided in, for example, the 3600 series natural gas engines commercially available from Caterpillar Inc. of Peoria, Ill.
The trend continues to operate these engines under lean-burn conditions. Lean burn refers to the burning of fuel with an excess of air in an internal combustion engine (i.e. lean fuel/air ratio). The excess of air in a lean burn engine combusts more of the fuel and emits fewer unwanted emissions. However, the lean fuel/air ratio can make it difficult to consistently achieve complete and thorough combustion within the main combustion chamber.
The components of internal combustion engines can be subjected to very high temperatures. For example, the surfaces defining the orifices of the nozzle of a member of a fuel combustion system, such as a prechamber nozzle, for example, can be subjected to very high temperatures as a result of the flow and temperature characteristics of the fuel mixtures traveling therethrough. In the case of a prechamber assembly, the high temperatures can be caused by the velocity of the fuel/air mixture entering the nozzle through the orifices and the ignition flame front discharged from the nozzle out through the orifices. As a result, the high temperatures to which the orifices are subjected can cause degradation of the nozzle and impair the function of the nozzle over time.
U.S. Pat. No. 8,813,716 is entitled, “Pre-combustion Chamber Tip,” and is directed to a pre-combustion chamber tip for an internal combustion engine. The pre-combustion chamber tip has a first body portion and a second body portion. The first body portion has a pre-combustion chamber located within. The first body portion has a terminal end with a plurality of orifices configured to direct expanding gases out of the pre-combustion chamber. The second body portion is attached to the first body portion. The second body portion has an exterior surface, a cooling fluid opening formed in the exterior surface, a cooling fluid passage in fluid communication with the cooling fluid opening, and a ridge associated with the cooling fluid opening. The ridge extends from the exterior surface and is configured to divert cooling fluid flow into the cooling fluid opening and cooling fluid passage.
There is a continued need in the art to provide additional solutions to enhance the performance of components of a fuel combustion system such as those in a prechamber assembly. For example, high temperatures in the orifice area of a gas engine prechamber nozzle can limit its service life and negatively affect the prechamber assembly's allowable design parameters. As such, there is a continued need to enable a prechamber assembly of a fuel combustion system to operate so as to enhance the combustion of fuel within the system while managing the heat generated during use of the prechamber assembly to improve its durability and usefulness.
It will be appreciated that this background description has been created by the inventors to aid the reader, and is not to be taken as an indication that any of the indicated problems were themselves appreciated in the art. While the described principles can, in some respects and embodiments, alleviate the problems inherent in other systems, it will be appreciated that the scope of the protected innovation is defined by the attached claims, and not by the ability of any disclosed feature to solve any specific problem noted herein.